Method and apparatus for displaying and cutting out region of interest from picture

ABSTRACT

A method of displaying and cutting out a region of interest. Upon depicting contour lines indicating regions of interest, respectively, on a display screen, the regions of interest are displayed with contour lines differing from one region to another in accordance with the order in which the regions of interest are designated. The contour displayed is scanned in the four directions leftward, rightward, upward and downward. For the inaccessible regions which are located outside of the contour and which could not have been reached by the scanning line, one of the upward and downward scannings and one of the leftward and rightward scannings are repeated until the inaccessible regions are no longer present.

BACKGROUND OF THE INVENTION

The present invention relates to a method of displaying regions ofinterest (ROI) of a picture, a method of cutting out a region from thepicture and an apparatus for carrying out these methods.

According to a typical one of the methods known heretofore forestablishing a region of interest on a picture, a region designatingdevice such as a mouse or the like is employed for marking the region ofinterest on the picture. In the case where there are present a pluralityof regions of interest on a picture, the ordinal numbers indicating thesequence in which the regions of interest are designated are displayedin the vicinity of the regions of interest in one-to-one correspondencefor the purpose of distinctively specifying the regions of interest. InFIG. 1 of the accompanying drawings, there are shown two regions ofinterest on a medical picture. Referring to the figure, when a region 2Aindicated by a broken line is designated in a picture 2 generated on adisplay screen 1, the ordinal number "1" indicating its turn in thesequence of designation is displayed in the vicinity of the region 2A.Subsequent designation of a region 2B indicated also by a broken line inFIG. 1 is accompanied with the display of the ordinal number "2" in thevicinity of the region 2B.

According to a second one of the methods known heretofore, a region ofinterest is prepared independently of a picture, wherein a region of thepicture which coincides with the region of interest is cut out. Moreparticularly, referring to FIG. 2A of the accompanying drawings, aregion of interest on a picture is first designated by means of anindicating device such as a mouse or the like while viewing the picture,whereby the region of interest is prepared as a figure or contour suchas a line diagram 3A (hereinafter referred to as the mouse-drawn contouror diagram or figure or the like). Next, a circumscribing line 3B isgenerated for the mouse-drawn contour 3A. This can be accomplished by acomputer.

In the generation of the circumscribing line 3B, a circle of a radius rhaving the center at a point 3b located near the mouse-drawn contour 3Ais designated. When at least a point 3a on the mouse-drawn contour 3Aexists within the circle, then the point 3b is regarded as a point whichconstitutes a part of the circumscribing line 3B. Next, after moving toa point disposed a predetermined distance from the point 3b in thedirection indicated by an arrow in FIG. 2B, a similar procedure isrepeated. In this manner, the circumscribing line 3B for the mouse-drawncontour 3A is generated. Parenthetically, the circle of the radius r maybe represented by a matrix of 3×3 pixels, for example, in the case of adigital picture.

By making use of the mouse-drawn contour diagram 3A and thecircumscribing line diagram 3B, a region of interest is cut out from thereal picture.

The first mentioned prior art method is certainly advantageous wherebythe operator that can easily specify the region of interest by virtue ofthe ordinal numbers affixed to the regions. However, a disadvantage ofthis prior art method can be seen in that portions of the picturelocated closely to the affixed numbers are difficult to view.

The second mentioned prior art method is notable in that memories forstoring the line diagrams (i.e. the mouse-drawn contour diagram and thecircumscribing line diagram) are prepared separately for cutting out aregion from a picture. This method however suffers in that the procedurefor preparing the circumscribing line diagram is required and that notonly the circumscribing line diagram but also the mouse-drawn contourdiagram has to be used for cutting out the region of interest from thepicture. Besides, in the case of the second mentioned method, it isrequired to identify discriminatively the portions located inside andoutside of the mouse-drawn contour, the procedure for which however isextremely complicated to disadvantage.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method ofdisplaying a region or regions of interest of a picture, a method ofcutting out the region of interest and an apparatus for carrying outthese methods in which the regions of interest can be specified withoutresorting to the use of identification numbers and in which a contourdiagram for cutting out the region of interest can be generated withoutusing the circumscribing line diagram.

According to the present invention, it is contemplated to identifydiscriminantly the regions of interest with the aid of the attributes ofcontour lines thereof. With the phrase "attributes of the contour line",it is intended to mean the types or species of the line (such as a solidline, a broken line, a single-dot phantom line, a double-dot phantomline, a solid line, a thin line, densities and colors of the line andthe like).

According to an aspect of the invention, it is proposed that all thepixels of the whole display screen are at first initialized to zero orto specific characters "A" uniformly or in a specific pattern (referredto as the pattern having a pattern value of "P₁ "), by way of example,whereas the pixels on the line of the mouse-drawn contour are set to avalue differing from the above-mentioned initial pattern value such asexemplified by "P₂ ". In the following description, it is assumed thatall the pixels are initialized to the initial pattern value "P₁ " forthe convenience of discussion. The contour diagram thus generated isthen scanned in the four directions, i.e. from the left to the right,from the right to the left, from the top to the bottom and from thebottom to the top, respectively, whereupon encountering the first pixelof a pattern value "P₂ " different from "P₁ " on the mouse-drawn contourline in the course of scanning in a given one of the above-mentioneddirections, that scan is then terminated to start the scan along thenext scanning line. The area enclosed by the pixels "P₂ " thus obtainedcan then be specified as the region to be cut out. In this manner, allthe pixels located within the region to be cut out may be changed inrespect to the pattern value thereof from "P₁ " to "P₃ " or,alternatively, the pattern value of all the pixels within the region tobe cut out may remain the same with all of the pixels located outside ofthe region being changed from "P₁ " to "P₃ ". In any case, the regionslocated inside and outside of the mouse-drawn contour line can bediscriminated with the different pattern values of the pixels. Thus,there is realized a contour line for cutting out the region of interest.There may appear a mouse-drawn contour of such a complicated shape thatmakes it difficult to discriminate the portions located inside andoutside of the mouse-drawn contour. To deal with such a complicatedmouse-drawn contour, it is proposed according to another aspect of theinvention that, after the contour line for cutting out the region ofinterest has been obtained, unique processing is performed in an effortto correctly distinguish the portions located outside and inside of themouse-drawn contour. In this manner, the mouse-drawn contour of acomplicated shape may be such as exemplified in FIG. 2A and have deeprecesses of intricate shapes as designated by 3c and 3d. According tothe unique processing taught by the invention, these contour portions 3cand 3d are compared with patterns prepared previously for the purpose ofcollation to thereby differentiate the inside and outside regions fromeach other, in view of the fact that the contour portions 3c and 3d aredifficult to identify by the scanning in the four directions mentionedabove.

By virtue of the feature of the invention that the order or sequence inwhich the regions of interest have been designated can be recognizedwith the aid of the attributes of the contour lines, any particularregion of interest can easily be identified or selected.

Furthermore, owing to the scan processing performed conveniently in thefour directions for discriminating the regions located outside andinside of the contour line for cutting out the region of interest, theprocessing time can be reduced significantly as compared with the priorart processing.

Further still, even the contour portion of a complicated shape whichrenders it impossible or difficult to discriminatively identify theregions located outside and inside thereof from each other through thescanning in the four directions can be defined through the additionalprocessing performed by making use of the collation patterns.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2A and 2B are views for illustrating the prior art method ofdisplaying and cutting out a region of interest from a picture;

FIG. 3 is a schematic block diagram showing a general arrangement of anapparatus according to an embodiment of the present invention;

FIGS. 4A and 4B are views for illustrating a method of displayingregions of interest on pictures according to an exemplary embodiment ofthe invention;

FIG. 5 is a flow chart for illustrating a first extraction processing;

FIGS. 6 and 7 are views for illustrating in more detail the processingshown in FIG. 5;

FIG. 8 is a view for illustrating inaccessible regions making appearancein the extraction processing illustrated in FIG. 5;

FIGS. 9A and 9B are views for illustrating how to process theinaccessible region;

FIG. 10 is a view showing in general an additional processing flowaccording to another embodiment of the invention;

FIG. 11 is a view showing in greater detail the additional processingflow;

FIG. 12 is a view for illustrating the additional processing flow shownin FIG. 11; and

FIGS. 13A and 13B are views showing a relation between a mouse-drawncontour diagram and a picture from which a region of interest is to becut out.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 3 is a schematic block diagram showing a general arrangement of animage processing system according to a preferred or exemplary embodimentof the invention. As can be seen in the figure, there are connected inparallel to a bus 10, a central processing unit or CPU 11, a high-speedarithmetic operation circuit 12, a memory 13, a disk file 14, memories15, 17 and 19 and a controller 21. Cathode-ray-tube or CRT displays 16,18 and 20 are connected as terminals to the memories 15, 17 and 19,respectively. A mouse 22 is connected to the controller 21 as aterminal.

The CPU 11 is responsible for management or control of the whole systemas well as for image processing. Programs for this end are stored in thememory 13 which additionally stores various data inclusive of those forthe work areas. The disk file 14 stores various data bases and variousdata (including picture or image data).

The memories 15, 17 and 19 are provided distinctively from one anotheras a character display memory, a mouse-drawn contour display memory anda picture display memory, respectively. The CRTs 16, 18 and 20 areprovided for displaying different pictures. By way of example, the CRT16 is provided for displaying a medical picture or image, the CRT 18 isfor displaying a mouse-drawn contour diagram and the CRT 20 is fordisplaying a region of interest to be cut out from the medical picturewith the aid of the mouse-drawn contour diagram. It should however bementioned that the various display functions mentioned above may beperformed solely with the CRT 16. In that case, the other CRTs 18 and 20may be employed for other purposes or uses.

The mouse 22 is used for inputting a mouse-drawn contour by way of thecontroller 21 under command of operator, whereby the contour diagram isdisplayed on the CRT 18 in the case of the illustrated embodiment of theinvention.

A new or novel part of the illustrated system resides in the high-speedarithmetic operation circuit 12. This circuit is constituted by adedicated hardware (or firmware in more strictive sense) which includesa read-only memory or ROM, an arithmetic unit and a memory. Contents ofthe processing are designated by a microprogram stored in the ROM. Thearithmetic unit performs the processing in accordance with the contentsof the processing stored in the ROM to thereby designate finally aregion of interest by making use of read/write operations performed inthe memory.

There are two types of processings to be executed by the microprogram.The first is a processing for discriminantly determining the order orsequence of designations of regions of interest by making use of theattributes of the contour lines. In this manner, it is to be noted thatthere is previously programmed in the ROM what types or species of linesare to be used for displaying the regions of interest in accordance withthe order or sequence in which the regions of interest are to bedesignated. However, since this processing is simple, it mayalternatively be performed by the CPU 11.

The second is a four-directional scan processing for discriminantlyidentifying the portions located inside and outside of the mouse-drawncontour line and a subsequent processing. This second processing issimple in its nature. However, in view of the fact that the same stepsare executed repeatedly many times, this second processing is profitablysuited to be performed by firmware with a microprogram which is softwarehaving a close affinity to the hardware. The contents of the secondprocessing will hereinafter be described in greater detail.

FIG. 4A is a view showing examples of the regions of interest designatedsequentially by making use of the attributes of the contour lines. Thewhole display screen area of the CRT 16 is divided into nine subareas ina matrix array of 3 rows and 3 columns (a sort of windowing fixed orvariable) such that the mouse-drawn contour can be generated in any ofthe subareas by using the mouse 22. Further, it is contemplated thatdifferent pictures are displayed separately and individually in the ninesubareas and that the mouse-drawn contours can be generatedindependently of one another.

Now, it is assumed that a picture 16A is specified, a mouse-drawncontour indicating a region of interest is designated in the picture16A, and that a certain statistic processing is to be performed on amedical picture within the contoured region.

First, the procedure for designating a region of interest in a picturedisplayed in the subarea 16A is started, wherein a boundary (a rectanglein a thick solid line) for the subarea 16A is automatically displayed.Once the boundary has thus been established, the object for theprocessing is limited to the picture displayed on the subarea 16A. Anarrow marker 22B interlocked with the mouse 22 can be moved only withinthe subarea 16A and is prevented from moving to any of the othersubareas. Of course, the boundary line may be drawn by manuallyoperating the mouse 22 correspondingly. To this end, the boundary linemay be drawn with the mouse while depressing a button 22A.

After generation of the boundary line, a marker 22B is moved bymanipulating the mouse 22B to thereby designate a region of interest 22Cindicated by a thick solid contour line. The thick solid contour linedisplayed indicates the region of the picture designated first with themouse 22.

In succession to the display of the thick solid contour line, statisticprocessing of the density of the picture region enclosed by the contourline is performed, the results of which is shown in FIG. 4B, only by wayof example. More specifically, referring to FIG. 4B, there are shown inthe row labeled "Example 1" the results of the static processingconcerning a standard deviation, a maximum value, a minimum value, thenumber of pixels and mean value.

Through the similar procedure, the subarea 16B is selected, wherein aregion 22D of interest is designated. Since this is the seconddesignation of the region of interest, the latter is indicated by abroken line. Further, as a third designation of the region of interest,the subareas 16C is designated, wherein a region 22E of interest isindicated by a single-dot phantom line. In this manner, the order of thefirst to third designations can be shown by the solid line, the brokenline and the single-dot phantom line, respectively. In FIG. 4B, examplesof the statistic processing for the regions of interest 22C, 22D and 22Eare shown at (1), (2) and (3), respectively.

According to the instant embodiment of the invention, the regions ofinterest can be displayed by changing the type or species of the contourline for every region of interest, whereby they can be easily specifiedor discriminantly identified. In particular, it is noted thatdiscriminative identification of the pictures is facilitated for theoperator. In the case of a color CRT display, the regions of interestmay be discriminantly indicated by changing the colors of themouse-drawn contour lines.

FIG. 5 shows a first processing flow chart for extracting a picture tobe cut out from a region delimited by the mouse-drawn contour lineaccording to another embodiment of the invention, while FIG. 6 and FIG.7 illustrate concrete examples of the extraction from the memory.Referring to FIG. 5, all the pixels (picture elements) of the displayscreen are at first initialized. By way of example, all the pixels areset to a pattern value P₁ (step F₁). Next, a mouse-drawn contour linefor cutting out a region of interest is generated with the pixels on thecontour line being changed from the pattern value of P₁ to P₂. Thus, themouse-drawn contour line is specified (step F₂).

After having specified the mouse-drawn contour, processing steps F₃ toF₆ are executed. In FIG. 5, there are shown in the step blocks F₃ to F₆the contents of processing by scanning from the left toward the right,scanning from the right toward the left, scanning from the top towardthe bottom and scanning from the bottom toward the top. When the pixelof the pattern value P₂ is detected on the mouse-drawn contour line inthe course of scanning, then the scan is terminated, and the next scanis initiated. As the result of this processing, the pixels belonging tothe contour line segments I to IV, as well as those located outside ofthese line segments, are changed from the pattern value of P₁ to P₃.

More specifically, referring to FIG. 6, the contour line segment I isfirst obtained by scanning the mouse-drawn contour diagram 3 from theleft-hand side. Thereafter, the contour line segment II can be extractedby scanning the mouse-drawn contour diagram in the direction from theright to the left. Subsequently, the mouse-drawn contour diagram isscanned from the top toward the bottom to thereby extract the contourline segment III. Finally, the contour segment IV is extracted throughthe scanning from the bottom toward the top. The contour line segmentIII can not be extracted either by the scanning from the left to theright or the scanning from the right to the left but can be extractedonly by the scanning from the top to the bottom. Similarly, the contourline segment IV can not be extracted through the scannings in the threedirections from the left to the right, from the right to the left orfrom the top to the bottom, but can only be extracted by the scanning inthe direction from the bottom to the top.

FIG. 7 illustrates, by way of example, extraction of the contour linesegment III. From the figure, it will be seen that the contour segmentIII can be detected only by the scanning S₃ in the direction from thetop toward the bottom and can not be detected either by the scanning S₁in the direction from the left to the right or by the scanning S₂ fromthe right to the left.

Next, an example of extracting a contour line segment from a mouse-drawncontour diagram of a complicated shape will be explained by referring toFIG. 8.

FIG. 8 shows a mouse-drawn contour diagram of an intricate shape havinga number of deep recesses. As will be seen in the figure, contour linesegments Q₁ to Q₆ remain undetected with the pixels thereon being leftwith the pattern value of P₁ even after the scannings in thefour-directions mentioned above. This means that the pixels of thepattern value P₁ existing on the segments Q₁ to Q₆ are regarded as beinglocated inside of the region to be cut out, resulting in a defectivecut-out picture.

Accordingly, for the inaccessible regions which could not be reached bythe scanning in the four directions, two additional scannings in thedirections from the left to the right and from the top to the bottom areperformed for the mouse-drawn diagram obtained through the processingshown in FIG. 5. For these additional scannings, collation patterns forallowing the inside and the outside of the mouse-drawn contour line tobe discriminated are previously prepared for identifying whether a pixelof concern is located outside or inside of the mouse-drawn contour lineby determining whether or not the pixel of concern belongs to thecollation pattern. It should be added that the two additional scanningsmentioned above may be effected in the directions from the right to theleft and from the bottom to the top.

The relationship between the collation patterns and the inside/outsidediscriminations are listed in the following table 1.

                  TABLE 1                                                         ______________________________________                                        Type     Pattern       Results of collation                                   ______________________________________                                        (a)      P.sub.2 -(P.sub.1 ˜P.sub.1)-P.sub.3                                                   (P.sub.1 ˜P.sub.1) is changed to P.sub.3         (b)      P.sub.2 -(P.sub.1 ˜P.sub.1)-P.sub.2                                                   (P.sub.1 ˜P.sub.1) is left unchanged             (c)      P.sub.3 -(P.sub.1 ˜P.sub.1)-P.sub.2                                                   (P.sub.1 ˜P.sub.1) is changed to                 ______________________________________                                                               P.sub.3                                            

In the above table, (P₁ ˜P₁) represents a succession of the pixels ofthe pattern value P₁ inclusive of the single existence of the pixel ofP₁. The collation patterns can be applied in con, non to the scanning S₁in the direction from the left to the right and the scanning S₃ from thetop to the bottom. In the case of the scanning S₁ from the left-handside, the pattern of type (a) represents a region in which the pixel ofP₂ (the pixel on the mouse-drawn contour) is located at the leftmostend, being followed by a succession of the pixels of P₁ and then thepixel of P₃ at the rightmost end. In the case of the scanning from thetop to the bottom, the pattern of type (a) represents a region in whichthe pixel of P₂ exists at the top, which is followed by a succession ofthe pixels of P₁ and then the pixel of P₃ at the bottom.

Regions represented by the patterns of type (b) and (c) can be definedsimilarly to the pattern of type (a).

When the patterns of the types (a) and (c) are validly applied, thesuccessive pixels of (P₁ ˜P₁) are all changed to P₃. When the pattern oftype (b) is validly applied, the pixels of (P₁ ˜P₁) are left as theyare.

More specifically, reference is made to FIG. 9A which shows, by way ofexample, an inaccessible region Q₁ (=Q₁₁ +Q₁₂) which could not bereached in the first extraction processing and is left as it is. In thesecond scanning S₁ in the direction from the left to the right, thepixels on the scanning line within the region Q₁ are in the pattern ofP₂ -(P₁ ˜P₁)-P₂. This corresponds to the collation pattern of type (b)listed in the table 1. Accordingly, the pixels of (P₁ ˜P₁) are left asthey are.

On the other hand, in the second scanning S₃ in the direction from thetop to the bottom, the pixels on the individual scanning lines withinthe region Q₁₁ assume a pattern of P₃ -(P₁ ˜P₁)-P₂ which coincides withthe pattern type (c) in the table 1. Accordingly, all the pixels of P₁within the region Q₁₁ are changed from P₁ to P₃.

In the scanning S₃ from the top to the bottom, the pixels within theremaining subregion Q₁₂ of region Q₁ are in a pattern of P₂ -(P₁˜P₁)-P₂. Thus, the pixels corresponding to (P₁ ˜P₁) remain as they are,without being processed.

Now, the scannings S₁ and S₃ are performed once again. In the scanningS₁, the pixels are in the state such as illustrated in FIG. 9B, whereinthe pixels in the region Q₁₁ are changed to P₃ through the precedingscan processing S₃. Accordingly, the scanning S₁ within the region Q₁₂results in a pixel pattern of P₃ -(P₁ ˜P₁)-P₂ which coincides with thepattern type (c) in the table 1. Accordingly, all the pixels of (P₁ ˜P₁)are changed to P₃.

In the succeeding scan S₃, there exist no pixels which are to be changedfrom P₁ to P₃. Accordingly, the scanning S₃ at this time results in nochange of P₁ to P₃.

Parenthetically, it is sufficient to perform the additional scanprocessings S₁ and S₃ only within a rectangular region circumscribingthe mouse-drawn contour. In scanning the whole picture, there may arisesuch a case in which all the pixels on the scanning lines are P₃(meaning that all the pixels are located outside of the mouse-drawncontour). In that case, all the pixels of (P₃ ˜P₃) are left as they are.

The above description has been made in conjunction with the region Q₁.It should however be understood that the regions Q₂ and Q₆ (FIG. 8) areprocessed similarly. The additional scan processings S₁ and S₃ arerepeated, respectively, until there exist no regions that could not bereached or accessed.

FIG. 10 is a flow chart outlining the additional processing. Referringto the figure, at a step F₁₁, a flag D₁ indicating the horizontalscanning (i.e. the scanning S₁ in the direction from the left to theright) and a flag D₂ indicating the vertical scanning (i.e. the scanningS₃ in the direction from the top to the bottom,) are initialized (i.e.D₁ =0, D₂ =0). Needless to say, these flags D₁ and D₂ are used fordetermining whether or not the scan processing S₁ and/or S₃ is to berepeated.

Next, solidification processing in the horizontal direction is executed.With the phrase "solidification processing", it is intended to mean theprocessing for changing the pixels of (P₁ ˜P₁) to those of P₃. So far asthere exists at least one pixel having the pattern value P₁ changed toP₃ within the range scanned, the flag D₁ is set to "1", while it is leftat "0" when no change is made in the pattern value at all (step F₁₂).

Subsequently, the solidification processing is executed in the verticaldirection. When there exists even a single pixel having the patternvalue of P₁ changed to P₃, the flag D₂ is set to "1" and otherwise it isleft as "0" (step F₁₃).

When the solidification processings in the horizontal and verticaldirections have once been performed, it is then checked whether theflags D₁ and D₂ are "0" or not (step F₁₄). When D₁ ="0" with D₂ ="0",then the processing comes to an end, because further repetition of theprocessing can no longer bring about the change of the pattern value toP₃. If D₁ ="1" with D₂ ="1" or if D₁ ="1" with D₂ ="0" or if D₁ ="0"with D₂ ="1" the step F₁₁ is repeated because there is the possibilitythat the pixel of the pattern value P₁ may be changed to P₃ at theadditional processing steps (F₁₁ to F₁₃). Those processings are repeatedthree times in the case of the example illustrated in FIGS. 9A and 9B.

FIG. 11 is a flow chart illustrating in greater detail the additionalhorizontal processing. The term "flag" used in the flow chart means theflag D₁ used in the horizontal processing, and reference symbols AD₁ andAD₂ represent the addresses of the start and end pixels, respectively,of a pattern which is to be compared with the collation pattern.Further, in the following description of the processing shown in thisflow chart, it is assumed that the mouse-drawn contour diagram, shown inFIG. 12 and derived from the first extraction processing, is used.

Referring to FIG. 11, the flag is "0" with AD₁ and AD₂ being "0" and"AD₁ +1" respectively, at a step 210. Pattern comparison starts from twopixels. So far as the inaccessible region which could not be reachedexists, the flag is set to "1" after the processing, while it remains"0", if otherwise. At a step 220, data is read out from the address AD₁.This data is represented by X₁. At a step 221, it is decided whether thepattern value of X₁ is P₂ or P₃ or alternatively P₁.

When X₁ =P₂, the procedure jumps to a step 230 where data is read outfrom the address AD₂. This data is represented by X₂. When this data X₂is of the pattern value P₂, there is no need for the change orreplacement. At a step 234, the leading end of the pattern to becompared is shifted by one pixel by incrementing the addresses (i.e. AD₁←AD₁ +1 with AD₂ ←AD₁ +1), whereupon return is made to the step 230.When X₂ =P₁, the address AD₂ is incremented by "1" at a step 235 toextend the pattern to be compared by one pixel, whereupon the step 230is repeated. Thereafter, even when a pixel having the value P₁ isencountered in a pattern of P₂ P₁ P₁ P₁ P₂ (such as the pattern 30 shownin FIG. 12), there is no necessity to change the pixel value. Byrepeating the steps 230, 231 and 235, the address AD₂ is sequentiallyshifted. When X₂ equal to P₃ is encountered at a given place in thecourse of the repetition (corresponding to the pattern 31 in FIG. 12),the processing procedes to a step 231 where any pixel of P₁ existingbetween the addresses AD₁ and AD₂ are replaced by P₃. Further, the flagis set to "1", being followed by a step 233 where the address AD₁ isincremented such that AD₁ ←AD₂ +1, to thereby set the pixel next to thatreplaced by P₃ at the start address, whereon the step 233 is regained.

When it is determined at the decision step 221 that X₁ =P₁, the addressAD₁ is incremented by one to shift the start of the pattern forcomparison by one pixel, whereupon return is made to the step 220.

On the other hand, when the decision step 221 results in that X₁ =P₃,the procedure jumps to a step 240 at which data of AD₂ is read out. Thisdata is represented by X₂. When X₂ =P₃, the addresses are incremented ata step 244 such that AD₁ ←AD₁ +1 and AD₂ ←AD₁ +1, to thereby shift byone pixel the pattern subject to the comparison, whereupon return ismade to the step 220. On the other hand, when X₂ =P₁, the processingproceeds to a step 245 at which the address AD₂ is incremented, beingfollowed by the return to the step 240. Further, when it is found at thestep 241 that X₂ =P₂ as in the case of the pattern 32 shown in FIG. 12,any pixel of P₁ existing between those of AD₁ and AD₂ are replaced bythe pixel of P₃ at a step 242 and then the flag is set to " 1". At astep 243, the address AD₁ is incremented such that AD₁ ←AD₂ +1 tothereby set the pixel succeeding to the pixel replaced by P₃ at thestart address, whereupon return is made to the step 220.

This first additional processing in the horizontal direction iscompleted when the address AD₁ has attained a predetermined value. (i.e.at the end of the picture).

The scan processing in the vertical direction is executed in accordancewith the processing flow similar to what has been described above.

Next, by reference FIGS. 13A and 13B, description will be made of theprocessing for cutting out a region of interest from a picture underconsideration. When a mouse-depicted contour is drawn on the imagememory, the image or picture data at the corresponding memory locationswill be erased. In order to evade such inconvenience, there are providedseparately a memory (40 in FIG. 13A) dedicated to the storage of themouse-drawn contour diagram and a memory (50 in FIG. 13B) for storing apicture from which the region of interest is to be cut out. The rows andcolumns of the memories 50 and 51 are provided in one-to-onecorrespondence or at a predetermined ratio. On the CRT, the picturesstored in both memories are displayed in superposition to allow a region41 of interest to be depicted on the CRT display screen while viewingthe picture 51 from which the region of interest is to be cutout.

As a result, the mouse-drawn contour 41 is recorded on the memory 40without injuring the picture data on the image memory 50 at all.

In the actual cut-out processing, the contents of the memories 40 and 50are compared with each other on an address basis, whereby the pictureportion on the memory 50 corresponding to the mouse-drawn contour 41 iscut out.

Parenthetically, the pixels of P₂ on the mouse-drawn contour may bechanged to the pixels of P₁ upon comparison, and thereafter theaddress-based comparison may be performed.

As an alternative, instead of displaying the mouse-drawn contour on thepicture from which a region of interest is to be cut out, the former maybe designated on another CRT (or a blank region of the CRT on which thepicture of concern is displayed) while viewing the picture. In thiscase, the mouse-drawn contour is automatically written in the othermemory (or on the other region of the memory).

The concept of the invention underlying the processing for extractingthe region of interest described above can equally be applied todivision of a picture.

More specifically, when the display area is divided into subareas, asillustrated in FIG. 4A, a memory having a capacity corresponding to thesize of all the pictures being displayed is prepared.

When a mouse-drawn contour diagram is generated on a picture beingdisplayed on a subarea for designating a region of interest, themouse-drawn contour diagram is stored in the above-mentioned memory asit is and additionally displayed on the screen. Subsequently, extractionof the mouse-depicted diagram is performed. To this end, a limit rangedefined by the boundary line of the subarea is provided. It is thenunnecessary to scan the whole display but sufficient to perform thescanning only within the subarea. Thus, by designating the boundary linesimultaneously with the start of the drawing of a contour with themouse, it is possible to perform the extraction and cut-out processingonly within the designated boundary. Parenthetically, definition orestablishment of the boundary line may be effected directly under thecommand of the mouse. In the case of the embodiment of the inventiondescribed above, the scanning of a whole picture is renderedunnecessary, whereby the time involved in the scanning can be reducedsignificantly. Further by designating a range of the memory whichcorresponds to the subarea, the time taken for scanning the memory canbe reduced correspondingly.

According to another embodiment of the invention, memories for storingthe mouse-drawn contour are provided at a plurality of stages. In thiscase, even when the mouse-depicted contours or figures overlap oneanother on the display screen, they can be stored in the associatedmemories, respectively, whereby the cutting-out of region of interestcan be realized correctly without exerting any influence to the othermouse-depicted figures.

It should also be mentioned that the contour of concern can be depictednot only with the mouse but also by using other types of input devices.

Further, picture scanning sequence may be started in any given one ofthe directions without being limited to the sequence or order describedhereinbefore in conjunction with the exemplary embodiments of theinvention.

Many different embodiments of the present invention may be constructedwithout departing from the spirit and scope of the invention. It shouldbe understood that the present invention is not limited to the specificembodiments described in this specification. To the contrary, thepresent invention is intended to cover various modifications andequivalent arrangements included within the spirit and scope of theclaims.

I claim:
 1. A method of displaying regions of interest of a picture tobe displayed, said method comprising the steps of:a) dividing saidpicture to be displayed into a plurality of subpictures; b) designatingregions of interest on a given one of said subpictures; c) establishing,as a range for the designation of the regions of interest, an areainside of a boundary defining said subpicture in which the regions ofinterest designated are located, in response to a signal commanding thestart of designation of the regions of interest; d) determining an orderin which said regions of interest are to be designated; and e)displaying said regions of interest with lines of different attributesin accordance with said order of designation.
 2. A method of displayingregions of interest according to claim 1, wherein said differentattributes comprise different types of lines.
 3. A method of displayingregions of interest according to claim 1, wherein said differentattributes comprise different densities of the lines.
 4. A method ofdisplaying regions of interest according to claim 1, wherein saiddifferent attributes comprise different colors of the lines.
 5. A methodof cutting out a region of interest from a displayed picture, saidmethod comprising the steps of:a) drawing a contour of said region ofinterest on said picture being displayed; b) defining pixel informationof said contour as a pattern value P₂ while defining pixel informationof portions other than said contour as a pattern value P₁ ; c) scanningsaid contour in four directions from the top, the bottom, the left andthe right, respectively; d) extracting, as contour lines, only thoseportions of said contour that can be viewed in each of said scanningdirections; e) changing the pixel information of portions locatedoutside of said contour lines from the pattern P₁ to a pattern P₃ ; f)storing said patterns P₁, P₂ and P₃ as contour information for saidregion of interest; and g) extracting picture information correspondingto the pixels of pattern P₁ within the contour from the information ofthe picture being displayed.
 6. A method of cutting out a region ofinterest from a picture being displayed according to claim 5, whereinsaid step a) includes a step of initializing to said pattern P₁ thepixels, within a predetermined range of said picture being displayed,over which a contour of said region of interest is to be drawn.
 7. Amethod of cutting out a region of interest from a picture beingdisplayed according to claim 5, wherein said step a) of drawing acontour of said region of interest further comprises the stepsof:dividing a picture to be displayed into a plurality of subpictures;designating regions of interest on a given one of said subpictures;responding to a signal commmanding the start of designation of saidregions of interest to thereby establish, as a range for the designationof said regions of interest, an area inside of the boundary definingsaid given one subpicture in which said designated regions of interestdesignated are located; determining an order in which said regions ofinterest are to be designated; and displaying said regions of interestwith lines of different attributes in accordance with said order ofdesignation.
 8. A method of cutting out a region of interest from apicture being displayed according to claim 5,wherein said step a) ofdrawing said contour comprises the steps of: reading out pictureinformation from a picture information storage memory to display saidpicture information on a display screen; reading out contour informationfrom a contour information storage memory to display said contourinformation on said display screen simultaneously with the display ofsaid picture; and said storing step f), storing said contour informationin said contour information storage memory, wherein said extracting stepg) further comprises the steps of: comparing said contour informationwith said picture information on said contour information storage memoryand said picture information storage memory; and extracting pictureinformation of addresses corresponding to said pattern P₁ of saidcontour information from said picture information.
 9. A method ofcutting out a region of interest from a picture being displayedaccording to claim 5, wherein said steps a) to g) are executed throughmicroprogram processing.
 10. A method of cutting out a region ofinterest from a picture being displayed, said method comprising thesteps of:a) drawing a contour of said region of interest on said picturebeing displayed; b) defining pixel information of said contour as apattern P₂ while defining pixel information of portions other than saidcontour as a pattern P₁ ; c) scanning said contour in four directionsfrom the top, the bottom, the left and the right, respectively; d)extracting, as contour lines, only those portions of said contour thatcan be viewed in each of said scanning directions; e) changing the pixelinformation of portions located outside of said contour lines from thepattern P₁ to a pattern P₃ ; f) determining the presence or absence ofany inaccessible region which is located outside of said contour andwhich can not be reached by a scanning line during said scannings in thefour directions; g) additionally scanning said inaccessible regionincapable of having been reached either in a leftward or rightwarddirection and either in the upward or downward direction; h) changingsuccessive pixel patterns P₁ to pattern P₃ when a pattern of informationof successive pixels obtained by said additional scanning coincides witha pattern for collation consisting of P₂, P₁ ˜P₁, P₃ a pattern forcollation consisting of P₃, P₁ ˜P₁, P₂ where P₁ ˜P₁ represents asuccession of P₁ ; i) determining the presence or absence of anyinaccessible region which could not be reached after said additionalscanning; j) repeating said steps g) to i) until said inaccessibleregions, incapable of having been reached, are no longer present; k)storing said patterns P₁, P₂ and P₃ as information of the contour ofsaid region of interest; and l) extracting said picture informationcorresponding to said pattern P₁ internally of said contour from saidpicture being displayed.
 11. A method of cutting out a region ofinterest from a picture being displayed according to claim 10, whereinsaid step a) includes a step of initializing to said pattern P₁ thepixels, within a predetermined range of said picture being displayed,over which a contour of said region of interest is to be drawn.
 12. Amethod of cutting out a region of interest from a picture beingdisplayed according to claim 10,wherein said step h) of changing thepixel pattern P₁ to P₃ comprises the steps of: setting a predeterminedvalue for a flag D₁ provided for indicating the presence or absence ofthe change of the pattern P₁ to the pattern P₃, when said pattern P₁ hasbeen changed to the pattern P₃ in the scanning in either the leftward orrightward direction; setting a predetermined value for a flag D₂provided for indicating the presence or absence of the change of thepattern P₁ to the pattern P₃, when said pattern P₁ has been changed tothe pattern P₃ in the scanning in either the upward or downwarddirection; and wherein said decision step includes: repeating saidadditional scanning step g) when at least one of said flags D₁ and D₂ isset to said predetermined value; and indicating transition to said stepk) unless both of said flags D₁ and D₂ are set to said predeterminedvalue.
 13. A method of cutting out a region of interest from a picturebeing displayed according to claim 10, wherein said step a) of drawing acontour of said region of interest further comprises the stepsof:dividing a picture to be displayed into plurality of subpictures;designating regions of interest on a given one of said subpictures;responding to a signal commanding the start of designation of saidregions of interest to thereby establish as a range for the designationof said regions of interest an area inside of the boundary defining saidgiven one subpicture in which said designated regions of interest arelocated; determining an order in which said regions of interest are tobe designated; and displaying said regions of interest with lines ofdifferent attributes in accordance with said order of designation.
 14. Amethod of cutting out a region of interest from a picture beingdisplayed according to claim 10,wherein said step a) of drawing thecontour comprises the steps of: reading out picture information from apicture information storage memory to display said picture informationon a display screen; reading out contour information from a contourinformation storage memory to display said contour information on saiddisplay screen simultaneously with the display of said picture; whereinsaid storing step k), includes a step of storing said contourinformation in said contour information storage memory, wherein saidextracting step 1) includes the steps of: comparing said contourinformation with said picture information on said contour informationstorage memory and said picture information storage memory; and cuttingout picture information of addresses corresponding to said pattern P₁ ofsaid contour information from said picture information.
 15. A method ofcutting out a region of interest from a picture being displayedaccording to claim 10, wherein said steps a) to l) are executed throughmicroprogram processing.
 16. An apparatus for displaying regions ofinterest, comprising:a) means for dividing a display screen into aplurality of subareas; b) means for setting said subareas as ranges inwhich said regions of interest area are to be displayed; c) means forregistering therein different attributes of lines used for indicatingsaid regions of interest in correspondence to a sequence in which saidregions of interest are to be designated; d) means for inputting saidregions of interest; e) means for determining said sequence in whichsaid regions of interest are designated to be inputted; and f) means fordiscriminantly displaying said regions of interest according to saiddifferent attributes of the lines.
 17. An apparatus for displayingregions of interest according to claim 16, wherein said differentattributes comprise different types of lines.
 18. An apparatus fordisplaying regions of interest according to claim 16, wherein saiddifferent attributes comprise different densities of the lines.
 19. Anapparatus for displaying regions of interest according to claim 16,wherein said different attributes comprise different colors of thelines.
 20. An apparatus for cutting out a region from a picture,comprising:a) means for displaying a contour of a region of interest ona display screen, said contour being bounded by a contour line; b) meansfor setting pixel information of said contour as a pattern P₂ whilesetting pixel information of portions other than said contour as apattern P₁ ; c) means for scanning said contour in four directions fromthe top to the bottom, from the bottom to the top, from the left to theright and from the right to the left, respectively; d) means forrecognizing intersection points between scanning lines, generated uponsaid scanning, and a line indicating said region of interest that arealso points on said contour line in said region of interest; e) meansfor changing said pixel information of the pixels existing between saidscanning lines and said contour line from said pattern P₁ to P₃ ; f)first decision means for determining the presence or absence ofinaccessible regions which are located outside of said contour line andwhich could not be reached by said scanning lines during said scanningin said four directions; g) means for additionally scanning saidinaccessible regions in direction either from the left to right or fromthe right to the left and in the direction either from the top to thebottom or from the bottom to the top; h) second decision means fordetermining the presence or absence of an inaccessible region whichcould not be reached in the additional scanning; i) means for repeatingsaid additional scanning until there no longer exists any inaccessibleregions; j) means for storing said patterns P₁, P₂ and P₃ as informationfor said contour of said region of interest when said inaccessibleregions no longer exist; and k) means for extracting picture informationcorresponding to said pattern P₁ inside of said contour from informationof said displayed picture.
 21. An apparatus for displaying regions ofinterest according to claim 20, wherein said second decision meansincludes:means for comparing information of successive pixels with apattern for collation consisting of P₂, P₁ ˜P₁, P₃ or a pattern forcollation consisting of P₃, P₁ ˜P₁, P₂, where P₁ ˜P₁ represents asuccession of P₁ ; and means for changing said successive pixels of P₁to the pixels of P₃ when coincidence is found as the result of saidcomparison.
 22. An apparatus for displaying regions of interestaccording to claim 21, wherein said means a) to j) are constituted bymicroprogram processing means.
 23. An apparatus for displaying regionsof interest according to claim 20, wherein said display meanscomprises:a picture information storing memory; a contour storingmemory; means for reading out picture information from said pictureinformation storing memory and for displaying said picture informationon said display screen; and means for reading out said contourinformation from said contour storing memory and for displaying saidcontour information on said display screen simultaneously with thedisplay of said picture information; wherein said means for storing saidpatterns P₁, P₂ and P₃ includes means for storing said contourinformation in said contour storing memory, said extracting meansincludes means for comparing said contour information and said pictureinformation with each other from said contour storing memory and saidpicture information storing memory, respectively; and means forextracting means said picture information having addresses correspondingto the pattern P₁ of said contour information.
 24. An apparatus fordisplaying regions of interest according to claim 23, wherein saiddisplay means further comprises:means for dividing a display screen intoa plurality of subareas; means for setting said subareas as ranges inwhich the regions of interest area are displayed; means for registeringtherein different attributes of lines used for indicating said regionsof interest in correspondence to a sequence in which said region ofinterest are designated; means for inputting said regions of interest;means for determining said sequence in which said regions of interestare designated to be inputted; and means for displaying said regions ofinterest discriminantly with the aid of said different attributes ofsaid lines.
 25. An apparatus for displaying regions of interestaccording to claim 24, wherein said means a) to j) are constituted bymicroprogram processing means.